The present invention relates to data input/output operation methods and systems, and particularly to a data input/output method and system suitable for use in semipermanent high-speed input or output of a great amount of digitized image data, such as is transmitted from a larger-capacity data source, for example a satellite.
In a typical computer, the data input/output operation is performed in accordance with a predetermined timing under the control of the computer, or as in the case of communications control, the data input/output is similarly performed after a preliminary signal exchange among a plurality of sending and receiving apparatus has been completed. That is, in any case, a program chiefly controls the input/output of data.
In the field of satellite image processing, however, it is a common practice that the image data transmitted from a satellite to earth is recorded on a high-density magnetic tape or the like, which serves as a special high-speed data recording means on the ground, and then the recorded data is reproduced therefrom and applied to a computer. In this case, the data input to the computer is semipermanently received so that the computer is required to process the data flow without delay. In other words, it is necessary that the input/output operation is not performed under the control of a program, but is performed under the control of a large-capacity data source, such as a satellite.